If you are in an account and go to add a contact, the Account field in the contacts page is not autofilled with the account name as it used to be. Therefore when you submit the contact, they are not linked to the account. Did this change for a reason or is something not working correctly?
I have tested this in SuiteCRM 7.1.1 on linux running php 5.3 and mysql 5.5 and this works as required. Are you getting any errors in your console log? To test this do Ctrl+Shift+J(Chrome) or Ctrl+Shift+K(Firefox) and look for any errors. Did your install run without error? Have you performed a Quick Repair & Rebuild, Rebuild Relationships and retried?
Did a Quick Repair and that appears to have fixed the issue. Not sure why I didn’t try that to begin with.